The standard index figures provide one number that’s comparable across all connected SIL rams, regardless of breed. “The higher the number, the better the ram.”
Dual purpose rams have a New Zealand Maternal Worth figure (NZMW); the average NZMW is 1600. While terminal rams have a New Zealand Terminal Worth (NZTW) and its average is 1150. Terminal rams have lower scores than maternal rams, because their index is calculated from a smaller number of traits.
The index also extends to specific traits, like FE tolerance or resistance against internal parasites. For instance, if you’re looking for facial eczema tolerance, identify breeders who prioritise FE, then ask them for NZMW + X (X representing the FE trait).
Or, if you’re looking for resistance to internal parasites, identify breeders who prioritise this trait, then ask them for NZMW + FEC.
The same rule of thumb applies to the health traits: The higher the number, the better the ram.
Bottom line message for farmers
When you enquire about rams this year, ask your breeder for NZMW and/or NZTW figures:
- NZMW – if you breed your own replacements.
- NZTW – if you need a terminal sire.
The higher the figure, the better the ram.
Find out more
For more, visit ramindex.co.nz